Traditionally, in order to adjust resistance value of semiconductor silicon wafers, microelements (dopants) such as phosphorous and arsenic are doped while developing N-type silicon monocrystals.
The doping on silicon monocrystals produced by Czochralski method is conducted by blowing a gas in which the microelements are volatilized onto silicon melt (see e.g. JP-A-2001-342094 (P. 3-6, FIGS. 1, 2)) or by directly adding solid microelements into silicon melt (see e.g. JP-A-2004-137140 (P. 5-7, FIG. 4)).
In order to blow the microelement gas to silicon melt, solid microelement is initially housed in an accommodating portion of a doping device. Then, the solid microelement is vaporized in a high-temperature atmosphere in a chamber of a pull-up device, thus blowing the microelement gas to the surface of the silicon melt.
Alternatively, in order to directly add a solid microelement into silicon melt, the solid microelement is put into an injection tube (doping device) having sealed upper and lateral portions and a latticed (netted) lower portion. The lower portion of the injection tube is immersed in the silicon melt to vaporize the microelement by the temperature of the silicon melt.